This application includes a computer program listing Appendix A submitted on a compact disc (two copies). The file on the compact discs is 9415-9024 appendix.txt, created Mar. 1, 2001 and having 65,536 bytes. The information on the compact discs, including Appendix A, is incorporated herein by reference.
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent and trademark office patent file or records, but otherwise reserves all copyright rights whatsoever,
The present invention is related to passenger detection systems, and in particular to passenger detection systems that can readily classify an attribute of a passenger of an automobile in which an air bag device is installed.
Air bag devices ease the shock that a passenger experiences during an automobile collision. Air bags are installed in front of the driver""s and passenger""s seats. Air bags may be installed in other locations, such as to the side of a forward facing passenger.
In a typical air-bag system, the control system includes a control circuit that receives a signal from an electrical acceleration sensor (shock detection sensor), and transmits control signals to the gates of normally-open semiconductor switching elements. The switching elements are respectively connected in parallel paths between a system operating voltage and ground. Each path includes a safing sensor, a squib circuit and the switching element. The squib circuits are connected to the gas sources of the air bag devices.
In operation, the air bag control system only deploys the air bags when both of the safing sensors close, and when the electrical acceleration sensor closes. Current flows from the system operating voltage to ground through each of the squib circuits, thereby causing respective gas sources to deploy (inflate) the air bags.
Many air bags are designed to deploy in front of the torso of an adult passenger seated in the seat. When a rear facing infant seat (hereafter RFIS) is located on the front passenger seat, it is desirable for the passenger-side air bag not to deploy. It may also be desirable for the passenger-side air bag not to deploy for a forward facing child seat (hereafter xe2x80x9cFFCSxe2x80x9d) or child. Likewise, deployment may be limited for side impact airbags based on whether a child or short person is leaning towards the air bag.
Passenger detection sensor types have been proposed for detecting a RFCS, an FFCS or children. Systems using electric fields to detect characteristics of a load in a seat are disclosed in U.S. Pat. Nos. 5,948,031, 6,329,913 (Ser. No. 09/413,099, filed Oct. 5, 1999), and U.S. Pat. No. 6,329,914 (Ser. No. 09/678,215, filed Sep. 29, 2000). Other systems using capacitive sensing, such as systems to detect a change in phase or frequency due to the presence of a passenger, have also been proposed. Both types of systems rely on transmission and reception from one or more antenna or electrodes.
Since airbags deploy forcefully and quickly, sensors for correctly determining whether any passenger is in a desirable or undesirable location are desired. Such sensors may prevent injury. By correctly avoiding deployment of the airbag when no passenger is present, replacement costs may be avoided.
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiment described below includes multiple sensor vehicle occupant detection for air bag deployment control.
A humidity and/or moisture sensor is used in addition to sensors for detecting the characteristic of a load or passenger. The measurements of the sensors for detecting the characteristic of the passenger are altered to account for humidity in the air or wetness adjacent the electrode. Humidity readings may also be altered based on the wetness adjacent the humidity sensor.
An occupants connection to ground is also used in addition to sensors for detecting the characteristics of a load or occupant. The connection to ground of any occupant is measured using the sensors for detecting the characteristics of the occupant. The measurements relating to characteristics of the occupant are altered in response to the detected level of connection to ground.
In accordance with a first aspect, a vehicle passenger detection system and associated method for sensing a passenger in a passenger seating area is provided. The system includes a passenger detection system and a humidity sensor connected with the passenger detection system. The passenger detection system is responsive to the humidity sensor.
In accordance with a second aspect, another vehicle passenger detection system and associated method for sensing a passenger in a passenger seating area is provided. The system includes a passenger detection system and a moisture sensor connected with the passenger detection system. The passenger detection system is responsive to the moisture sensor.
In accordance with a third aspect, a vehicle passenger detection method and associated system for sensing a passenger in a passenger seating area is provided. The method comprising the acts of: (a) connecting a first electrode to ground; (b) measuring a first signal at a second electrode while the first electrode is connected to ground; (c) disconnecting the first electrode from ground; (d) measuring a second signal at the second electrode with the second electrode is disconnected from ground; and (e) determining a grounded state of the passenger as a function of the first and second signals.
Further aspects and advantages are described below.